U.S. Environmental Protection Agency
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Arsenic Monitoring Technologies
100
The U.S. EPA Environmental Technology Verification
(ETV) Program's Advanced Monitoring Systems (AMS)
Center, one of six technology areas under ETV, is
operated by Battelle under a cooperative agreement with
EPA. The AMS Center has verified ten technologies for
arsenic water monitoring1 (see verification reports at
http://wvvw.epa.gov/etv/verifications/vcenterl -21 .html).
Technology Description
Arsenic is typically measured using instruments that are
bulky and expensive to operate and maintain in a folly-
equipped laboratory. Field assays, in which lower sensi-
tivities may be acceptable for purposes of sample
screening or site surveys, strive for similar detection goals
as fixed laboratory methods, are relatively inexpensive,
and can produce a large number of screening results in a
short time. The ETV-verified arsenic monitoring
technologies are portable and designed for rapid on-site
analysis of arsenic in water. They can be categorized into
two monitoring technology classes: colorimetric and
anodic stripping voltammetry. Table 1 lists the ten
verified arsenic monitoring technologies by technology
class.
Colorimetric
The arsenic colorimetric test kits involve a chemical
reaction that converts the arsenic compounds (mostly
inorganic arsenic) present in the water into arsine gas.
The arsine gas is exposed to a test strip, usually paper
impregnated with a chemical that changes color from
white to shades of yellow or brown with increasing
arsine levels. The concentration of arsenic can be
approximated using a calibrated color scale. Measure-
ments with the colorimetric test kits are semiquantitative,
unless the field kits are equipped with a portable
colorimeter and/or a computer held scanner mat allows
for a quantitative determination of arsenic by quantifying
the color change.
Anodic Stripping Voltammetry
Anodic stripping voltammetry (ASV) is an analytical
technique in which analyte concentration is derived from
the measurement of electric current as a function of ap-
plied potential. Analysis involves reducing the analyte of
interest and plating the analyte onto an electrode by
applying a negative potential for a specific period of
time. The deposition serves to concentrate the analyte
from the solution onto the electrode in the metallic form.
After deposition, the potential is scanned toward positive
potentials and the analyte is men stripped off (i.e.,
oxidized), brought back into solution and measured
quantitatively relative to known standard solutions.
(Continued on page 2)
Arsenic and Its Regulatory
Background at a Glance
Arsenic occurs naturally in rocks, soil, wa-
ter, air, plants, and animals. It can be released
into water, including drinking water, through
natural processes such as erosion, or through
human actions, including agricultural applica-
tions (fungicides or rodenticides), mining, or
disposal of arsenic-laden consumer products
(wood preservative, paints, dyes, soaps, and
semiconductors). Studies have linked long-
term exposure to arsenic at various levels in
drinking water to cancer of the bladder, lungs,
skin, kidney, nasal passages, liver, and prostate.
Non-cancer effects of ingesting arsenic include
cardiovascular, pulmonary, immunological,
neurological, and endocrine (e.g., diabetes) ef-
fects.
In January 2001, based in part on the National
Academies of Science recommendation and to
protect consumers against the effects of long-
term chronic exposure to arsenic in drinking
water, EPA set a new drinking water standard
for arsenic at 10 parts per billion (ppb) with
compliance by all public water systems re-
quired by January 2006 (66 FR 6976).
Table 1.
Verified Arsenic Monitoring Technologies
Colorimetric Test Kits
Technology Name
Industrial Test Systems, Inc.
Quick™ II
Industrial Test Systems, Inc.
Quick™ Ultra Low II
Industrial Test Systems, Inc.
Quick™ Low Range
Industrial Test Systems, Inc.
Quick™ Low Range II
Industrial Test Systems, Inc.
Quick™
Peters Engineering AS 75
Envitop Ltd. As-Top Water
Anodic Stripping Voltammetry
(ASV)
Technology Name
Monitoring Technologies Inter-
national, Pty. Ltd. PDV 6000
with VAS Version 2.1 Software
TraceDetect Nano-Band™
Explorer
TraceDetect SafeGuard Trace
Metal Analyzer
The ETV Program operates largely as a public-private partnership through competitive cooperative agreements with non-profit research institutes. The
program provides objective quality-assured data on the performance of commercial-ready technologies. Verification does not imply product approval or
effectiveness. ETV does not endorse the purchase or sale of any products and services mentioned in this document.
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Table 2. Summary of Performance for Arsenic Monitoring Technologies
Technology*
A
Unitl
A
Unit 2
B
C
Unitl
C
Unit 2
D
E
F
G
H
1
Unitl
1
Unit 2
J
Accuracy8
(% relative bias)
-21 to 7
-21 to -8
-33 to 10
-46 to -4
-51 to 31
1to64
-24 to 18
-14.5 to 239
-47 to -8
8 to 83
2 to 70
2to>310
2 to 2900
Precision8
(% relative
standard de-
viation)
3 to 20
6 to 20
16 to 24
6 to 16
3 to 15
3 to 37
Oto14
Oto3
10 to 55
Oto29
Oto24
12to>71
0 to 111
Linearity8
slope
0.808
1.005
0.88
0.77
0.91
1.29
0.92
0.83
0.79
0.88
0.80
1.28
0.55
Intercept
0.060
1.618
-1.82
1.22
0.59
-5.56
0.22
2.61
-.03
-0.45
5.12
5.70
2.97
r2
0.9936
0.9942
0.9779
0.9934
0.9955
0.988
0.9948
0.9992
0.9904
0.988
0.979
0.923
0.66
False Positive
Ratec
(%)
0
0
0
0
0
13
0
3
0
0
3
13
18
False Negative
Ratec
(%)
4
22
19
42
38
7
14
0
62
5
0
0
30
Method Detection
Limits (MDL)8
(ppb)
3.75
2.87
7
8.6
5.8
14.2
2.9
3.1
1.2
Not Calculated
Not Calculated
28
Not Calculated
A Because the ETV Program does not compare technologies, the performance results shown in this table do not identify the technologies associated with
each result and are not in the same order as the list of technologies in Table 1.
B Technical operator sample results of performance test samples only
c Technical operator sample results of performance test samples, quality control samples, and environmental samples, relative to the 10 ppb maximum contami-
nant level for arsenic in drinking water
Verified arsenic monitoring technology- coiorimetric
(Continued from page 1)
Test Design and Verification Results
Arsenic measurements were compared to those from a laboratory-
based reference method—inductively coupled plasma mass
spectrometry (ICP-MS) performed according to EPA Method 200.8.
Technology performance was tested by analyzing performance test
(PT) samples, quality control (QC) samples, and environmental
samples for the evaluation of test parameters. Accuracy and linearity
were assessed by comparing technology results to those from the
reference method. Four aliquots of PT samples and environmental
samples were analyzed to assess precision. Seven aliquots of a PT
sample (five times the vendor-stated detection limit) were analyzed
to assess the detection limit. Potential matrix interference effects were
assessed with PT samples of 10 ppb arsenic concentration that contained
both low levels and high levels of potentially interfering substances. Some
technologies were verified using two identical units. Results from the two
units were statistically compared to evaluate inter-unit reproducibility.
Operator bias was assessed by statistically comparing data from two
operators (technical and non-technical). The rates of false positive and
. false negative results
ETV Advanced Monitoring Systems Center were evaluated relative
to the 10 ppb level of
detection. Table 2
provides a summary of
performance data for
some of the test
parameters.
Robert Fuerst, EPA, fuerst.robert@epa.gov
Tel: (919) 541-2220
Amy Dindal, Battelle, dindala@battelle.org
Tel: (561)422-0113
Verified arsenic monitoring technology— ASV
References
U.S. EPA ETV, http://www.epa.gov/etv/.
U.S. EPA Arsenic in Drinking Water, http:7/www.epa.gov/safewater/arsenic/.
Monitoring Arsenic in the Environment: A Review of Science and Technologies for Field Measurements and
Sensors, http://www.epa.gov/superfund/programs/aml/tech/news/asreview.htm.
EPA/600/S-07/005
January 2007
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